The present invention relates to a novel rifamycin derivative or salts thereof, a process for preparing the same and antibacterial agents containing the same as an effective ingredient. More particularly, the present invention relates to a novel rifamycin derivative having the formula (I): ##STR5## wherein X.sup.1 is an alkyl group with 1 to 6 carbon atoms or a cycloalkyl group with 3 to 8 carbon atoms; X.sup.2 is a hydrogen atom or an alkyl group with 1 to 4 carbon atoms; R.sup.1 is hydrogen atom or acetyl group; A is a group represented by the formula: ##STR6## wherein R.sup.2 is an alkyl group with 1 to 4 carbon atoms or an alkoxyalkyl group with 2 to 6 carbon atoms and R.sup.3 is an alkyl group with 1 to 6 carbon atoms or an alkoxyalkyl group with 2 to 6 carbon atoms, or a group represented by the formula: ##STR7## wherein ##STR8## is a 3 to 9 membered cyclic amino group with 2 to 8 carbon atoms, R.sup.4 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, or salts thereof, a process for preparing the same and antibacterial agents containing the same as an effective ingredient.
In the present invention, a 3 to 9 membered cylic amino group with 2 to 8 carbon atoms represented by the formula: ##STR9## means a group represented by the formula: ##STR10##
The rifamycin derivative of the present invention is a novel compound which has not yet been reported in the literature.